A 100Ω resistance and a capacitor of 100Ω reactance are connected in series across a 220V source. When the capacitor is 50% charged, the peak value of the displacement current is
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(a) […]
The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100V respectively in an L-C-R circuit. The power factor of this circuit is
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(a) 0.4 (b) 0.5 […]
Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?
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(a) R=20 Ω, L=1.5 H, C=35 μF (b) R=25 Ω, L=2.5 H, C=45 μF […]
A filament bulb (500W,100V) is to be used in a 230V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500w. The value of R is
The frequency of an alternating voltage is 50 cycles per second and its amplitude is 120 V. Then the r.m.s. value of voltage is
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(a) 84.8 V (b) 101.3 V (c) 70.7 […]
An a.c. supply gives 30 volt r.m.s which passes through a 10Ω resistance. The power dissipated in it is
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(a) 90 W (b) 90√2 W (c) 45 W (d) 45√2 W
Correct […]
A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when
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(a) number of turns in the coil is reduced […]
A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency. If an ac source, of 200 volt, 100 Hz, is connected across the coil, the current in the coil will […]
A 220 volts input is supplied to a transformer. The output circuit draws a current of 2.0 ampere at 440 volts. If the efficiency of the transformers is 80%, the current drawn by the primary […]
A series combination of resistor (R), capacitor (C), is connected to an AC source of angular frequency ω. Keeping the voltage same, if the frequency is changed to ω/3, the current becomes half of the […]
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